The present invention relates to a process for modeling control models applicable in the fields of steel plants, electric power plants, industrial plants and the like, and in particular, to a process for efficiently modeling a high precision control model on the basis of data collected from a control object.
A prior art data collecting method disclosed in JP-A No. 6-168222, which collects data from a control object for computer analysis, is provided with a means for collecting control information on the control object, and a memory for storing collected data independently, thereby enabling repeated simulation of the control object with the stored data.
Further, a prior art control model modeling method described in JP-A NO. 5-296923 discloses modeling of a control model on the basis of data collected from the control object, storing plural sets of relationships to cancel control errors in the control model relative to the control object using appropriate tune-in quantities to be applied when a corresponding relationship is identified by the neural network system.
The above-mentioned prior art methods, however, have the following problems.
The method of JP-A No.6-168222 discloses how to collect data from the control object, and how to store the collected data in memory of computers. However, it does not disclose nor suggest how to improve efficiency and accuracy of modeling of a control model using the collected data. Further, since a compensation of a delay from input to output in the control model is not considered, in modeling of a control model which requires different inputs and outputs at different time sequences, such compensation must be done manually. Still further, since data compression is not taken into consideration to compress stored data into an appropriate size and format that does not impede modeling of control models, data quantities accumulated in the computer become enormous when data collection is repeated.
The method of JP-A No.5-296923, although it attempts to improve the accuracy of the control model, does not take into consideration generalization of the data collected from the control objects. Thereby, when the collected data involves noise, this prior art method has the problem that the accuracy of the control model deteriorates. Further, since the validity of a control model constructed is not evaluated, when the control model constructed lacks generalization, control performance in an actual system using this control model deteriorates. Still further, since verification of the stored data stored in each subregion of the input and output regions is contemplated as to whether or not they are adequate in quantity and quality thereby to be able to construct a generalized control model, there is the problem that the accuracy of a particular output corresponding to a particular input in a particular subregion of a control model remarkably deteriorates.
The present invention has been contemplated to solve the above-mentioned problems associated with the prior art. A first object of the present invention is therefore to provide a modeling support system for modeling a control model and accurately evaluating the validity of the control model constructed.
A second object of the invention is to provide a modeling support system for modeling a control model which, when it is required to construct a control model to simulate a control object using different input and output data derived from the control object at different time sequences, compensates for a time delay of each input calculated on the basis of the operation of the control object, and stores such delay compensated data in a data base which can be directly used in constructing control models.
A third object of the invention is to provide a modeling support system for modeling a control model capable of notifying the operator of any subregion in the operational region of the control model which lacks accumulation of sufficient data, thereby avoiding any localized degradation in the performance of the control model.
A fourth object of the invention is to provide a modeling support system for modeling a control model capable of optimizing the size of its data base to store an enormous amount of data derived from its control object with a minimized loss of inherent statistical characteristics, and constructing control models using data stored in the optimized data base.
A fifth object of the invention is to provide an interactive modeling support system for modeling a control model which enables the operator to selectively actuate various control model modeling support means interactively and easily.
The first object of the invention can be accomplished by providing a modeling support system for modeling a control model to simulate a control object, comprising: a data collector for collecting data from the control object, separating the collected data into input data and its associated output data, and storing a plurality of data sets having the separated input data and its associated output data in a first data base; a data divider for dividing the plurality of the data sets stored in the first data base into a plurality of data groups each having the least statistical disparity therebetween; a second data base having a plurality of sub data bases for storing the plurality of subdivided data groups, respectively; a modeler for modeling control models to simulate the control object using a plurality of data stored in the first or the second data base; and a model evaluator for evaluating the control models constructed by the modeler using a plurality of data stored in the first or the second data base.
The second object of the invention can be accomplished by providing a modeling support system for modeling a control model comprising: a data collector for collecting data from a control object, separating the collected data into input data and output data for use in modeling a control model which can simulate the control object, determining a time at which a new input data corresponding to the output data should be collected, and storing a data set having input data collected at the determined time and the output data corresponding thereto in the first data base; and a modeler for modeling a control model for simulating the control object on the basis of the data set having the input data and the output data corresponding to each other having been stored in the first data base.
The third object of the invention can be accomplished by providing a modeling support system for modeling a control model which stores a plurality of data having been collected from a control object in a data base, and simulates the control object on the basis of the plurality of data stored in the data base, wherein the modeling support system further comprises a data quantizer: which divides input and output regions of the control model into a plurality of partial subregions, separates the plurality of data having been stored in the data base according to the partial subregions, and notifies the operator of any subregion having a smaller amount of data than a predetermined amount of data.
The fourth object of the invention can be accomplished by providing a modeling support system for modeling a control model, which stores a plurality of data having been collected from a control object in a data base, and simulates the control object on the basis of the plurality of data stored in the data base, wherein the modeling support system further comprises a data compressor which determines a smaller number of data combinations which can represent the plurality of data stored in the data base, and stores the smaller number of data combinations in the data base.
The fifth object of the invention can be accomplished by providing a modeling support system for modeling a control model comprising: a data collector for collecting data from a control object, separating the collected data into input data and output data for use in modeling a control model which can simulate the control object, determining a time at which a new input data corresponding to the output data should be collected, and storing a data set having the new input data collected at the determined time and the output data corresponding thereto in the first data base; a data divider for subdividing the plurality of data having been stored in the first data base into a plurality of sub data groups each having least statistical disparity from each other; a second data base having a plurality of sub data bases for storing the subdivided, plurality of data groups, respectively; a modeler for modeling a plurality of control models to simulate the control object using a plurality of data stored in the first or the second data bases; a model evaluator for evaluating the plurality of control models having been modified by the modeler alternatively using the plurality of data stored in the first or second data bases; a data quantizer which subdivides input and output regions of the control model into a plurality of subregions, subdivides the plurality of data having been stored in the data bases according to the subregions, and notifies, as a result of subdivision, the operator of any subregion having a smaller number of data than a predetermined number of data; a data compressor which determines a smaller number of data combinations which can represent the plurality of data sets stored in the first or the second data bases, and stores the smaller number of data combinations in the first or the second data bases; and a controller for independently controlling the data collector, the data divider, the modeler, the model evaluator, the data quantizer and the data compressor to start and stop operation thereof.
Use of the data collector according to the present invention eliminates the manual operation involved in the prior art which was required when constructing a control model using various input and output data obtained at different time sequences. Further, provision of the data utilization means according to the invention allows the operator instantly to know which data in which sub region should be sampled further in order to construct a more appropriate and accurate control model which can represent the control object. Still further, provision of the data divider and the model evaluator can verify validity of the control model that has been configured prior to actual application thereof. Use of the data compressor enables the size of the data base to be maintained at a proper size even if the quantity of data stored in the data base becomes enormous with time. In addition, use of the task controller enables the operator efficiently to select any of many methods provided for modeling a control model. Still more, in the embodiment of the invention in which different control models are evaluated and compared as to their accuracy and validity, an example is described of verifying which of the various different regression equations having different forms is more valid. However, it is not limited thereto, and other evaluation methods can be construed within the scope of the invention which can compare superiority between multi-layered neural networks each having different numbers of intermediate layers or different numbers of intermediate neurons, or between the regression model and the neural net, or which can determine a time in retrospect to collect data in a time series modeling.